Fair Value of Assets and Liabilities - Schedule of Assets and Liabilities Recorded at Fair Value on a Recurring Basis (Detail) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale, at fair value	$ 54,148	$ 55,366
Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale, at fair value	54,148	55,366
Fair value, Loans held for sale	93,176	119,112
Derivative assets	5,821	11,865
Derivative liabilities		2,180
Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale, at fair value	54,148	55,366
Fair value, Portfolio loans	17,215	13,780
Fair value, Loans held for sale	93,176	119,112
Fair Value, Measurements, Recurring [Member] | Derivative Loan Commitments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	2,202	11,821
Fair Value, Measurements, Recurring [Member] | Forward Loan Sale Commitments, including TBAs [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	3,619
Derivative liabilities		2,180
Fair Value, Measurements, Recurring [Member] | Forward Loan Sale Commitments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		44
Fair Value, Measurements, Recurring [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale, at fair value	54,148	55,366
Fair value, Portfolio loans	17,215	13,780
Fair value, Loans held for sale	93,176	119,112
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Derivative Loan Commitments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	2,202	11,821
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Forward Loan Sale Commitments, including TBAs [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	$ 3,619
Derivative liabilities		2,180
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Forward Loan Sale Commitments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		$ 44